This invention relates to the electrochemical cells, and in particular, to electrochemical cells provided with thermal control.
In the design of electrochemical cells, such as fuel cells and batteries of the type wherein reactant or process gas is conducted to the cells for electrochemical reaction, thermal control is a dominant factor. One seemingly desirable technique for realizing such control involves the utilization of the sensible heat from the process gas itself. In this technique the incoming process gas may be supplied to the fuel cell at a temperature below the desired cell operating temperature and at a flow level above that required to obtain a preselected cell output power. The additional process gas at the lower temperature then acts to remove heat simply by increasing its temperature during passage through the cell. In this type of system, it is also usual to recover unused outgoing heated process gas and, after suitable cooling and water removal, add same to the fresh supply gas to provide the required in-flow of process gas to the cell.
U.S. Pat. No. 3,198,664 discloses a typical system of the aforesaid type. A vastly improved system of this type is disclosed in U.S. patent application Ser. No. 923,363 assigned to the same assignee.
While the last mentioned system successfully provides temperature control, alternative systems are still being investigated.
It is an object of the present invention to provide an electrochemical cell system wherein thermal control is effected in a simple, passive and automatic manner.
It is a further object of the present invention to provide a fuel cell system wherein automatic and simple thermal control is provided during operating periods and automatic hermetic sealing during non-operating periods.